The Quality Index: A holistic Approach to describe Quality of Food

Summary

Adequately assessing the quality of food grown with different cultivation methods is a constant problem. According to SCHUPHAN (1961), food quality consists of three main characteristics: grading, technological quality and nutritional quality. The latter involves the ratio between beneficial and harmful substances. Yet it is obvious that more than merely summing various substances is needed to assess the quality of food properly. This problem has been previously discussed by SCHORMÜLLER (1974) and KLETT (1968). A concept of quality that embraces the plant as a whole (and the internal equilibrium of the individual components) requires bringing together the results of multiple investigations in an integrated accounting that registers even slight differ-ences. Examinations of food quality, moreover, have repeatedly tended to produce contradictory results. It may appear for example, that physiological imbalances within a plant create a low concentration of free amino acids - which is desirable since it theoretically implies a high concentration of essential amino acids (SCHUPHAN, 1976). However, the protein quality itself may remain low. Therefore, any statement concern-ing the quality of food which is based on a few parameters only proves to be insuffi-cient. Isolated approaches might lead to wrong conclusions. Also differences in parameters must not be summarized hierarchically because relatively small differences would become overestimated. The Quality Index, condensing as many parameters as possible in an integrated calculation, might provide a way out of this predicament.